/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/sysinfo.h>
#include <sys/inotify.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>

#include "log.h"
#include "readahead-common.h"
#include "util.h"
#include "missing.h"
#include "fileio.h"
#include "libudev.h"
#include "udev-util.h"

int file_verify(int fd, const char *fn, off_t file_size_max, struct stat *st) {
        assert(fd >= 0);
        assert(fn);
        assert(st);

        if (fstat(fd, st) < 0) {
                log_warning("fstat(%s) failed: %m", fn);
                return -errno;
        }

        if (!S_ISREG(st->st_mode)) {
                log_debug("Not preloading special file %s", fn);
                return 0;
        }

        if (st->st_size <= 0 || st->st_size > file_size_max) {
                assert_cc(sizeof(st->st_size) == 8);
                log_debug("Not preloading file %s with size out of bounds %"PRIu64,
                          fn, st->st_size);
                return 0;
        }

        return 1;
}

int fs_on_ssd(const char *p) {
        struct stat st;
        _cleanup_udev_unref_ struct udev *udev = NULL;
        _cleanup_udev_device_unref_ struct udev_device *udev_device = NULL;
        struct udev_device *look_at = NULL;
        const char *devtype, *rotational, *model, *id;
        int r;

        assert(p);

        if (stat(p, &st) < 0)
                return -errno;

        if (major(st.st_dev) == 0) {
                _cleanup_fclose_ FILE *f = NULL;
                int mount_id;
                union file_handle_union h = { .handle.handle_bytes = MAX_HANDLE_SZ, };

                /* Might be btrfs, which exposes "ssd" as mount flag if it is on ssd.
                 *
                 * We first determine the mount ID here, if we can,
                 * and then lookup the mount ID in mountinfo to find
                 * the mount options. */

                r = name_to_handle_at(AT_FDCWD, p, &h.handle, &mount_id, AT_SYMLINK_FOLLOW);
                if (r < 0)
                        return false;

                f = fopen("/proc/self/mountinfo", "re");
                if (!f)
                        return false;

                for (;;) {
                        char line[LINE_MAX], *e;
                        _cleanup_free_ char *opts = NULL;
                        int mid;

                        if (!fgets(line, sizeof(line), f))
                                return false;

                        truncate_nl(line);

                        if (sscanf(line, "%i", &mid) != 1)
                                continue;

                        if (mid != mount_id)
                                continue;

                        e = strstr(line, " - ");
                        if (!e)
                                continue;

                        if (sscanf(e+3, "%*s %*s %ms", &opts) != 1)
                                continue;

                        if (streq(opts, "ssd") || startswith(opts, "ssd,") || endswith(opts, ",ssd") || strstr(opts, ",ssd,"))
                                return true;
                }

                return false;
        }

        udev = udev_new();
        if (!udev)
                return -ENOMEM;

        udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev);
        if (!udev_device)
                return false;

        devtype = udev_device_get_property_value(udev_device, "DEVTYPE");
        if (devtype && streq(devtype, "partition"))
                look_at = udev_device_get_parent(udev_device);
        else
                look_at = udev_device;

        if (!look_at)
                return false;

        /* First, try high-level property */
        id = udev_device_get_property_value(look_at, "ID_SSD");
        if (id)
                return streq(id, "1");

        /* Second, try kernel attribute */
        rotational = udev_device_get_sysattr_value(look_at, "queue/rotational");
        if (rotational)
                return streq(rotational, "0");

        /* Finally, fallback to heuristics */
        look_at = udev_device_get_parent(look_at);
        if (!look_at)
                return false;

        model = udev_device_get_sysattr_value(look_at, "model");
        if (model)
                return !!strstr(model, "SSD");

        return false;
}

int fs_on_read_only(const char *p) {
        struct stat st;
        _cleanup_udev_unref_ struct udev *udev = NULL;
        _cleanup_udev_device_unref_ struct udev_device *udev_device = NULL;
        const char *read_only;

        assert(p);

        if (stat(p, &st) < 0)
                return -errno;

        if (major(st.st_dev) == 0)
                return false;

        udev = udev_new();
        if (!udev)
                return -ENOMEM;

        udev_device = udev_device_new_from_devnum(udev, 'b', st.st_dev);
        if (!udev_device)
                return false;

        read_only = udev_device_get_sysattr_value(udev_device, "ro");
        if (read_only)
                return streq(read_only, "1");

        return false;
}

bool enough_ram(void) {
        struct sysinfo si;

        assert_se(sysinfo(&si) >= 0);

        /* Enable readahead only with at least 128MB memory */
        return si.totalram > 127 * 1024*1024 / si.mem_unit;
}

static void mkdirs(void) {
        if (mkdir("/run/systemd", 0755) && errno != EEXIST)
                log_warning("Failed to create /run/systemd: %m");
        if (mkdir("/run/systemd/readahead", 0755) && errno != EEXIST)
                log_warning("Failed to create /run/systemd: %m");
}

int open_inotify(void) {
        int fd;

        fd = inotify_init1(IN_CLOEXEC|IN_NONBLOCK);
        if (fd < 0) {
                log_error("Failed to create inotify handle: %m");
                return -errno;
        }

        mkdirs();

        if (inotify_add_watch(fd, "/run/systemd/readahead", IN_CREATE) < 0) {
                log_error("Failed to watch /run/systemd/readahead: %m");
                safe_close(fd);
                return -errno;
        }

        return fd;
}

ReadaheadShared *shared_get(void) {
        _cleanup_close_ int fd = -1;
        ReadaheadShared *m = NULL;

        mkdirs();

        fd = open("/run/systemd/readahead/shared", O_CREAT|O_RDWR|O_CLOEXEC, 0644);
        if (fd < 0) {
                log_error("Failed to create shared memory segment: %m");
                return NULL;
        }

        if (ftruncate(fd, sizeof(ReadaheadShared)) < 0) {
                log_error("Failed to truncate shared memory segment: %m");
                return NULL;
        }

        m = mmap(NULL, sizeof(ReadaheadShared), PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0);
        if (m == MAP_FAILED) {
                log_error("Failed to mmap shared memory segment: %m");
                return NULL;
        }

        return m;
}

int block_get_readahead(const char *p, uint64_t *bytes) {
        struct stat st;
        char *ap = NULL, *line = NULL;
        int r;
        dev_t d;
        uint64_t u;

        assert(p);
        assert(bytes);

        if (stat(p, &st) < 0)
                return -errno;

        if (major(st.st_dev) == 0)
                return 0;

        d = st.st_dev;
        block_get_whole_disk(d, &d);

        if (asprintf(&ap, "/sys/dev/block/%u:%u/bdi/read_ahead_kb", major(d), minor(d)) < 0) {
                r = -ENOMEM;
                goto finish;
        }

        r = read_one_line_file(ap, &line);
        if (r < 0)
                goto finish;

        r = safe_atou64(line, &u);
        if (r < 0)
                goto finish;

        *bytes = u * 1024ULL;

finish:
        free(ap);
        free(line);

        return r;
}

int block_set_readahead(const char *p, uint64_t bytes) {
        struct stat st;
        char *ap = NULL, *line = NULL;
        int r;
        dev_t d;

        assert(p);
        assert(bytes);

        if (stat(p, &st) < 0)
                return -errno;

        if (major(st.st_dev) == 0)
                return 0;

        d = st.st_dev;
        block_get_whole_disk(d, &d);

        if (asprintf(&ap, "/sys/dev/block/%u:%u/bdi/read_ahead_kb", major(d), minor(d)) < 0) {
                r = -ENOMEM;
                goto finish;
        }

        if (asprintf(&line, "%llu", bytes / 1024ULL) < 0) {
                r = -ENOMEM;
                goto finish;
        }

        r = write_string_file(ap, line);
        if (r < 0)
                goto finish;

finish:
        free(ap);
        free(line);

        return r;
}
